Marasama wrote:Could the dimming be cause by a moon or ring system instead of the large radius?

That's what appears to be the case.

Lazarus wrote:From the paper...

The observations are more consistent with a circumplanetary (proto-satellite) dust disk or a ring system around the planet, as recently inferred for the planet Fomalhaut b in a similar young debris disk (Kalas et al. 2008).

Seems like the possible transit was detected as a result of the star being extensively monitored as it was at the time used as a photometric reference star (this was also before the existence of the dust disk was known). When these variations were detected, Beta Pictoris was dropped as a reference star and it stopped being so extensively monitored. Rather unfortunate, no?

Abstract wrote:We recently reported on the detection of a possible planetary-mass companion to Beta Pictoris at a projected separation of 8 AU from the star, using data taken in November 2003 with NaCo, the adaptive-optics system installed on the Very Large Telescope UT4. Eventhough no second epoch detection was available, there are strong arguments to favor a gravitationally bound companion rather than a background object. If confirmed and located at a physical separation of 8 AU, this young (~1500 K) massive Jovian companion (~8 Mjup) would be the closest planet to its star ever imaged, could be formed via core-accretion, and could explain most of the dust disk properties. Our goal was to return to Beta Pic five years later to obtain a second-epoch observation of the companion or, in case of a non-detection, constrain its orbit. Deep adaptive-optics L'-band direct images of Beta Pic and Ks-band Four-Quadrant-Phase-Mask (4QPM) coronagraph images were recorded with NaCo in January and February 2009. We also use 4QPM data taken in November 2004. No point-like signal with the brightness of the companion candidate (apparent magnitudes L'=11.2 or Ks~12.5$) is detected at projected distances down to 6.5 AU from the star in the 2009 data. As expected, the non-detection does not allow to rule out a background object; however, we show that it is consistent with the orbital motion of a bound companion getting closer to the star between 2003 and 2009. We place strong constraints on the possible orbits of the companion and discuss future observing prospects.

Looking through the paper, it seems that this non-detection of Beta Pictoris b does not rule out a transit way-back-yonder in 1981.

They wrote that Bet Pic b might be detectable again by the Fall of 2009. If it is detected, then perhaps we'll hear of it toward the end of 2009, or perhaps the beginning of 2010.

Assuming that the imaged companion candidate is indeed a planetary companion to Beta Pictoris, if the planet is imaged twice, and the locations of the planet in both images line up with the star, than the planet should either transit, or come close to it. I eagerly await a new detection

Abstract wrote:A point source observed 8 AU in projection from beta Pictoris in L' (3.8 micron) imaging in 2003 has been recently presented as a planet candidate. Here we show the results of L'-band adaptive optics imaging obtained at Keck Observatory in 2008. We do not detect beta Pic b beyond a limiting radius of 0.29 arcsec, or 5.5 AU in projection, from the star. If beta Pic b is an orbiting planet, then it has moved >=0.12 arcsec (2.4 AU in projection) closer to the star in the five years separating the two epochs of observation. We examine the range of orbital parameters consistent with the observations, including likely bounds from the locations of previously inferred planetesimal belts. We find a family of low-eccentricity orbits with semimajor axes ~8-9 AU that are completely allowed, as well as a broad region of orbits with e<~0.2, a>~10 AU that are allowed if the apparent motion of the planet was towards the star in 2003. We compare this allowed space with predictions of the planetary orbital elements from the literature. Additionally, we show how similar observations in the next several years can further constrain the space of allowed orbits. Non-detections of the source through 2013 will exclude the interpretation of the candidate as a planet orbiting between the 6.4 and 16 AU planetesimal belts.

As I understand it, it's assumed that the object should be detectable again toward the end of this year.

That paper has a rather interesting chart, which shows graphically, constraints on the orbital parameters of the object (a and e). Through 2012, the orbit gets more and more refined as continued non-detections are made. A non-detection by the end of 2013 would result in no acceptable possible orbits.

Borislav wrote:Protoplanetary disk spins right to left or left to right? Clockwise or counterclockwise?

In that image, the side of the disk on the left of the star is the receeding half, and the side of the disk on the right of the star is the approaching half. Clockwise looking down on the disk from "above."

Here, we show that the ~10 Myr β Pictoris system hosts a massive giant planet, β Pictoris b, located 8 to 15 AU from the star. This result confirms that gas giant planets form rapidly within disks and validates the use of disk structures as fingerprints of embedded planets. Among the few planets already imaged, β Pictoris b is the closest to its parent star. Its short period could allow recording the full orbit within 17 years.

This thing looks like an overgrown Jupiter analogue, probably a low-eccentricity orbit just beyond the snowline (i.e. where we expect to find the highest efficiency for gas-giant formation).

If I'm doing the mathematics right, the semi-amplitude of the astrometric wobble induced by this planet should be somewhere around 2-3 milliarcseconds (assuming a planetary mass 9 times Jupiter's, and a semimajor axis 8-13 AU), which is greater than the wobble induced by υ And d. I wonder how feasible this would be to measure. Definitely a dynamical mass measurement would be very useful for planetary evolution models.

Combining all the data together shows that the planet is moving around the star, as expected from the previous data. Analyzing these new observations, the team was then able to measure the mass of the planet, around 7 to 11 times the mass of Jupiter, and its effective temperature, between 1100 and 1700°C.

A 5 Micron Image of beta Pictoris b at a Sub-Jupiter Projected Separation: Evidence for a Misalignment Between the Planet and the Inner, Warped Diskhttp://arxiv.org/abs/1105.4607

We present and analyze a new M' detection of the young exoplanet beta Pictoris b from 2008 VLT/NaCo data at a separation of ~ 4 AU and a high signal-to-noise rereduction of L' data taken in December 2009. Based on our orbital analysis, the planet's orbit is viewed almost perfectly edge-on (i ~ 89 degrees) and has a Saturn-like semimajor axis of 9.55 (+3.46, -2.37) AU. Intriguingly, the planet's orbit is aligned with the major axis of the outer disk (Omega ~ 31 degrees) but probably misaligned with the warp/inclined disk at 50 AU often cited as a signpost for the planet's existence. Our results motivate new studies to determine exactly how $\beta$ Pic b sculpts debris disk structures and whether a second planet is required to explain the warp/inclined disk.

Our solutions also favor highly inclined solution with a peak around i=88.5° revealing a probable tilt with a perfectly edge-on configuration. We also derive prediction for transiting events. The solution is consistent with the planet being responsible for the 1981 transiting event.